Simons Array

With more than 20,000 state-of-the-art detectors, the Simons Array studied cosmic microwave background in incredible detail.

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A large white radio telescope with a bowl-shaped dish sits on a concrete platform in a desert, surrounded by mountains under a clear blue sky. — The Simons Array operated at one of the world’s premier sites for cosmological observations: the Atacama Desert in northern Chile. Courtesy of the Simons Array team

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Located at the James Ax Observatory at Cerro Toco in the Atacama Desert, Chile, the Simons Array measured patterns from the Big Bang, which helped astronomers make more precise measurements of the cosmic microwave background (CMB) and study the evolution of structure in the universe.

The Simons Array launched in 2012, and in mid-2016, united with the Atacama Cosmology Telescope (ACT) project to become the Simons Observatory, one of the largest experimental cosmology collaborations in the world. Formal funding for the Simons Array closed in July 2026.